Persistent surveillance is an imagery type that has proved to be useful for tactical and forensic uses in the Iraq and Afghanistan wars, and it will be effective, e.g., for use in of low level conflicts in the future. However, its synoptic coverage over hours, weeks, and months strains both available bandwidth and the logistics of transmitting the data. Current spatial compression solutions (JPEG, JPEG2000) can compress wide area persistent surveillance (WAPS) data to some degree, but are limited to 10 to 30 times compression. Motion compression algorithms such as H.264 can perform at up to 60 times compression for panchromatic data, but may lose very low pixel count movers at those ratios. Because of the amount of data generated by these platforms, a compression ratio of up to 500× is desirable. These kinds of compression ratios would allow for much broader dissemination of the data, and with the lower latency that is required to turn the information into actionable intelligence.
Future WAPS programs such as the Autonomous Real-time Ground Ubiquitous Surveillance-Imaging System program (ARGUS-IS) will generate very large data volumes. Current sensors, such as Constant Hawk, already challenge the manageable limits of available data storage, transfer and processing capabilities. As WAPS systems like ARGUS-IS continue to expand both frame rate and spatial resolution capabilities (Table 1), the “ballooning” data volumes create even more stressing data handling requirements.
TABLE 1ARGUS-IS System ParametersParameter DescriptionValueField of View (FOV)60°/60°Instantaneous Field of View (IFOV)26μradNadir GSD @ 20,000′ (~6 km)15.2cmNadir GSD @ 30,000′ (~9 km)22.9cmPixels1.8/109Full-field Update Rate12-15Hz
With a smaller instantaneous field of view, increased pixel count and higher anticipated frame rate, ARGUS-IS data rates will be on the order of 20 GB/s. The difficulty in managing such high data rates is further compounded by an increasingly ambitious concept of operations (CONOPs). For example, the ARGUS-IS data handling CONOPs calls for both the transmission of 50 regional data streams to the ground for real-time analysis, and for the storage of all collected data, for future forensic analysis.
WAPS data storage is a challenging problem. As previously stated, ARGUS-IS data rates are on the order of 20 GB/s. This is equivalent to about 1500 TB/day. Storing this quantity of data is an expensive (cost, power, weight) proposition for ground based archive systems, with an amplified expense for required on-board airborne archive solutions. Using 2008 hard drive technology, the number of drives required to store one day of ARGUS-IS data cost approximately $450K. Given the current Constant Hawk archival procedure of storing up to two months of data, storage of data rapidly becomes a cost prohibitive endeavor. In addition, the power requirements and associated weight for this quantity of hard drives is suboptimal for ground-based data archives and incompatible with airborne archive solutions, due to payload constraints (size, weight and power). Use of flash drive technology offers some relief with respect to power requirements, but is still well short of acceptable cost and weight. Data compression offers a practical solution to decreasing storage “expense” across the board.
WAPS data transfer rates are also a challenging problem. Table 2 provides a comparison of data transfer rates (bandwidth) and compression ratios required to successfully transmit ARGUS-IS data volumes over various ground (OC-192, OC-48 and T-1) and air (TCDL, CDL and Double CDL) data links. Without compression, sustainable real-time data transfer is unachievable. Even compression methods such as H.264, which gives a compression ratio of up to 60 times, but which loses very low pixel count movers in imagery, fall short of desired data transfer requirements, allowing for only a small fraction of the data to be transmitted in real-time. In contrast, compression ratios of 100 to 500 enable the use of high-bandwidth land-line transfers and offer a reasonable compromise at achieving air-link transfers, especially when used in conjunction with other ARGUS-IS data collection and exploitation procedures (i.e. transfer of only regional data streams over available down-links).
TABLE 2Data transfer and compression rate comparisonData LinkBandwidthCompression RequiredOC-1929,953.28Mb/s16OC-482,488.32Mb/s64T-11,544Mb/s100,000TCDL10.71Mb/s14,869CDL274Mb/s563Double CDL548Mb/s282
The present invention solves the problem of accurate registration of wide area data, thereby solving many problems in tracking, change detection, analysis, and compression. The present invention provides systems and methods for compression and analysis of persistent surveillance data, as will be explained below.